Tips for measuring resistance
Because the meter’s test current flows through all possible paths between the
test probe tips, the measured value of a resistor in a circuit is often different from
the resistor’s rated value.
The test leads can add 0.1 to 0.2 of error to resistance measurements.
To measure the resistance of the leads, touch the probe tips together and read
the resistance. If necessary, you can press the REL
button to automatically
subtract this value.
The resistance function can produce enough voltage to forward-bias silicon diode
or transistor junctions, causing them to conduct.
Do not use the 40 M range for measuring the in-circuit resistance to avoid this.
When meas uring large resi stance, reading may be uns tabl e due t o
environmentally induced elec trical noise. In this case, direct ly connect the
resistor to input terminals of the meter or shield the resistor at potential of the
COM input terminal to obtain stable reading.
For resistance above 1 M , the display may take a few seconds to stabilize. This
is normal for high resistance readings..
The met er has a circuit to prot ect the resistance range from over-voltage.
However, to prevent accidentally exceeding the protection circuit’s rating and to
ensure a correct measurement, NEVER CONNECT THE LEADS TO A SOURCE
OF VOLTAGE when the rotary switch is set to or or functions.
11
10
To improve the accuracy of dc voltage measurements taken in the presence of
ac voltages (such as, measuring the dc voltage of an amplifier in the presence of
an ac signal), measure the ac voltage first. Note the just measured ac voltage
range and select a dc volt age range that is the same or higher than t he ac
voltage range. This method improves the dc voltage accuracy by preventing the
input protection circuits from being activated.
Resistance ( , , ) Measurements
(Ohms, Diode, and Continuity)
Resistance is an opposition to current flow. The unit of resistance is the ohm ( ).
The meter measures resistance by sending a small current through the circuit.
Ranges available in resistance functions are :
400.0 , 4.000 k , 40.00 k , 400.0 k , 4 M , and 40 M
Warning
To avoid the risk of electrical shock and instrument damage,
input voltages must not exceed 1000 V dc or ac (rms). Do not
attempt to take any unknown voltage measurement that may
be in excess of 1000 V dc or ac (rms).
Caution
To avoid damaging the meter or the equipment under test,
remove all power f rom the circuit and discharge all high-
voltage capacitors before measuring resistance.
